Kingdom: Plantae

Phylum: Magnoliophyta -- flowering plants

Class: Magnoliopsida -- Dicotyledons

Order: Rubiales

Family: Rubiaceae -- Madder

Variety: Some older floras recognized var. echinospermum and var. aparine

Species Code: GAAP2

Common Name: catchweed bedstraw, cleavers

Origin: A weedy annual of disturbed places for which the nativity is unresolved. It is circumboreal and widespread in North America. See "characteristics" below for further information.

Rare: not by any stretch of the imagination!

Form: forb, annual, 10-100 cm tall, stems square, weak and sprawling, with retrorse hooks on the edges; roots fibrous.

Duration: annual

Longevity: annual

Habitat Type: prairie, shrub thickets, forest

Wetland Indicator Status: FACU

Leaves: usually in whorls of 6 or 8, narrow and cuspidate, margins and often the underside of the midvein with retrorse bristles.

Mature height: 4-40 inches

Flowers: few, perfect (or sometimes with sterile stamens or pistils, being functionally dioecious), borne terminally on axillary branches; corolla greenish white, 1-2 mm wide, rotate, with 4 ovate lobes; calyx obsolete.

Flower color: white

Bloom: May, June

Bloom starts on: late May

Bloom ends on: late June

Fruit: 2 nutlets, 1.5-5 mm long, covered with hooked bristles.

Characteristics:
A disagreeable and weedy annual for which the nativity is unresolved. Some sources claim it is native while others assert it is a European species. Flora of the Pacific Northwest (Hitchcock & Cronquist 1973) merely says it is "cosmopolitan". In his WSU master's thesis, Reid (1989) found most of the annual weedy Galium on the Palouse to be the European G. spurium. However, the basis for separating G. spurium and G. aparine is not widely accepted among taxonomists and G. spurium is usually reduced to synonymy with G. aparine. The taxonomy is further complicated by polyploidy and aneuploidy. Galium aparine is a worldwide species and it is certainly possible that there are both locally native and introduced genotypes present on the Palouse.
Reproduces sexually by seed.
500,000 seeds/lb (USDA NRCS PLANTS Database 2009).
Seeds do not persist in the seed bank beyond a second year (Malik & vanden Born 1988).
Fruit is a nutlet.
Flowers are usually perfect but may have either sterile stamens or sterile pistils and thus may be functionally dioecious.
Prefers areas with high soil nitrogen.
Dispersal is primarily by birds and mammals. The plants and seeds stick to fur, feathers, and clothing.
2n=20, 22, 42, 44, 63, 64, 66, ±86, 88 (Baldwin et al 2004). 2n=64 & 66 are the most common (Malik & vanden Born 1988).
Polyploidy and aneuploidy are both present (Malik & vanden Born 1988).
Has medicinal uses.

Sun requirement: full sun to shade

Soil moisture: xeric to mesic

Precipitation: 14-55 inches (USDA NRCS PLANTS Database 2009).

Stratification: cold moist

Seed yield: high

Seed first harvest: annual

Planting duration: annual

Seed size: medium

Herbaria: Specimen data and digital resources from The Consortium of Pacific Northwest Herbaria

Key words: forb annual native non-native introduced upland weed

Propagation:
Needs stratification (Baskin & Baskin 1988).
Fresh seed benefits from stratification but benefit declines with age. Seed germination is inhibited by light. Seeds have some after-ripening requirement (Malik & vanden Born 1988).
Germination is enhanced by light (Milberg et al 2000).
Very low germination at 20^oC in the dark without cold moist stratification (Maguire & Overland 1959).
Reproduces sexually by seed.

References:
Baldwin, B.G., S. Boyd, B.J. Ertter, D.J. Keil, R.W. Patterson, T.J. Rosatti, and D.H. Wilken (eds). 2004. Jepson Online Interchange for California Floristics. University and Jepson Herbaria, University of California, Berkeley, CA. Accessed 8/13/09 online at http://ucjeps.berkeley.edu/interchange.html

Baskin, Carol C., and Jerry M. Baskin. 1988. Germination Ecophysiology of Herbaceous Plant Species in a Temperate Region. American Journal of Botany 75:286-305.

Burrill, L.C. 1992. Catchweed Bedstraw, Galium aparine L. Pacific Northwest Extension Publication PNW 338. Oregon State University, Washington State University, and the University of Idaho.

Hitchcock, C. Leo, and Arthur Cronquist. 1973. Flora of the Pacific Northwest. Univ. of Washington Press. Seattle, WA.

Maguire, James D., and Alvin Overland. 1959. Laboratory Germination of Seeds of Weedy and Native Plants. Washington State Agricultural Experiment Station Circular 349, Pullman, WA. 15 p.

Malik, N., and W.H. vanden Born. 1988. The Biology of Canadian Weeds; 86. Galium aparine L. and Galium spurium L. Canadian Journal of Plant Science 68:481-499.

Milberg, P., L. Andersson, and K. Thompson. 2000. Large-seeded Species Are Less Dependent on Light for Germination than Small-seeded Ones. Seed Science Research 10:99-104.

USDA NRCS. 2009. The PLANTS Database (http://plants.usda.gov, 13 August 2009). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Links:
Plant Profile from the USDA PLANTS Database
Species information from the University of Washington Herbarium